LA CROSSE, Wis. — Tommy Biffle was watching the clock. With 45 minutes left in the final round, Biffle knew it was time to give up on the special smallmouth spot he’d been milking during the entire four-day Diet Mountain Dew Mississippi River Rumble presented by Power-Pole.

Thirty years of pro bass fishing tells you to when to make a move.

“If you sit there and hope they come and they don’t come, you have do something,” said Biffle, 55, of Wagoner, Okla.

Going into Sunday’s final round, Biffle was 7 ounces in back of leader Aaron Martens of Leeds, Ala. Biffle wanted the win, and especially the Bassmaster Classic berth that comes with an Elite trophy.

He abandoned the spot that had kept him in contention all week, and ran to a similar place he knew of nearby, with hard current between two islands. It hadn’t produced much before, but Sunday it paid off quickly.

“First throw, I caught a big one, second throw I caught a big one,” he said. He built his weight to 16 pounds, 13 ounces.

It was enough to get the better of Martens by 2 pounds, 7 ounces. Biffle won with a four-day total of 64-2. The win was the seventh in his Bassmaster career, and his fourth in the Elite Series. He also hit the $2 million mark in B.A.S.S. earnings.

Biffle’s prize was $100,000 and an instant-in for the 2014 Classic.

“Now I’ve got the Classic made. That’s the best feeling,” said Biffle, who had been facing an uphill battle to qualify based on Toyota Angler of the Year points.

Martens took second place with 61-11. Third was John Crews of Salem, Va., with 59-4. Taking fourth place with 56-8 was Fred Roumbanis of Bixby, Okla. Brandon Card of Caryville, Tenn., rounded out the Top 5 at 56-2. The 2012 Rumble winner, Todd Faircloth of Jasper, Texas, finished sixth at 55-15.

Like the other 99 Elite pros, Biffle had to overcome wind, muddy water, shifting currents and thunderstorms over four days on the Upper Mississippi River, the fishery that’s lately become so productive, it earned the No. 17 spot on Bassmaster Magazine’s “100 Best Bass Lakes” list of 2013.

The move he made to his last spot was critical for his win, but the majority of Biffle’s Rumble bass actually came from what he called it his “special smallmouth” place.

“It was the end of an island where the current was coming around the island. Over the years, it made a little ditch. The bass were holding in the ditch,” he said.

The ditch was actually a small depression, just a foot or two deeper than the surrounding water. It ran about 100 yards, but the bass were holding in a 20- to 30-yard stretch. The island lies only about 10 miles from the takeoff location, which gave Biffle time enough to run to other spots and catch the largemouth he weighed Sunday with four smallmouth.

Biffle’s winning rig was a 7/16-ounce Biffle HardHead jig made by Larew, which has a swivel hook to give the bait more action. He rigged the jig with a green pumpkin Larew Biffle Bug.

“It’s always been great in rocks, but this is the first time I’ve ever fished it in pure sand. Smallmouth love it,” he said.

For Martens, it was déjà vu. He had the same near-miss almost exactly a year ago on the same fishery in an Elite event. He was just 7 ounces behind leader Faircloth going into the final day of that 2012 event, but the bass chose to wrap their lips around a huge hatch of mayflies, ignoring the lures he was throwing. Martens finished 4-3 out of first for a fifth-place finish.

“Second place isn’t bad,” said Martens, who knows how it feels. Sunday’s finish was his 12th at second place on the Bassmaster circuit.

Martens relied on a dropshot rig for three days, making long casts and giving the lure subtle shakes. His lures were 4 1/2- and 6-inch thick-bodied Fat Roboworms; and a 6-inch original Roboworm, all in the color Aaron’s Magic. When the bite got tougher, he rigged the soft plastics wacky-style.

But on the final day, just when he needed it most, Martens’ dropshot wasn’t producing. He made a move and helped his weight, but the action was slow for the bigger ones.

He returned to his “glory spot” and picked up a 3/4-ounce football jig made by Davis Jigs with a green-pumpkin, twin-tailed Zoom grub.

“Then I smoked them,” he said, “but it wasn’t enough. He (Biffle) got me by over 2 pounds. He caught them really good.”

Both Biffle and Martens got an inadvertent helping hand from Brandon Palaniuk, the first-day leader, and seemingly the leader with 6 pounds on Martens after Day 2. That evening, Palaniuk’s second-day weight was disqualified. B.A.S.S. officials received a protest against Palaniuk, and then determined he had unintentionally culled a bass in Minnesota. Minnesota law does not allow culling of bass on border waters, while Wisconsin does.

The Rumble’s outcome changed up the standings in the season-long Toyota Bassmaster Angler of the Year race. Edwin Evers of Talala, Okla., still leads, and with a wider margin, thanks to his 11th-place finish Sunday. Evers, shooting for his first Angler of the Year title, is working hard to stay ahead of a who’s-who list of title holders.